Metallic elements and oxides and their relevance to Laurentian Great Lakes geochemistry.

Malachi N Granmo,Sara P Post,Lawrence M Zanko,Euan D Reavie

doi:10.7717/peerj.9053

Abstract

The Laurentian Great Lakes are the most studied system in lake geochemistry and have well-preserved chronological profiles. Metals play numerous critical roles in natural and anthropogenic characteristics of lake ecosystems, so patterns in the historical records of metals from sedimentary cores provide important information about environmental baselines and human impacts. Relevant studies of Great Lakes geochemistry are listed, and we follow with encyclopedic descriptions of metals and their oxides in the lakes. These descriptions include likely natural and anthropogenic sources of elements, their known history from previous paleoecological studies, and their status as potential contaminants of concern. Despite the well-studied geology of the Great Lakes catchment, sourcing elements was sometimes difficult due to materials often being moved long distances by glaciation and the global prevalence of atmospheric pollutants. We summarized available information on metals and their roles as geochemical indicators in the Great Lakes.

Highlights

An understanding of past conditions is essential for potential remediation efforts in an aquatic system because it can be used to estimate natural baseline, remediation targets, timing and causes of impacts, and positive effects of existing remedial efforts
Geochemistry depends on location-specific soil and bedrock composition, so it is important to consider natural sources of inorganic materials relative to anthropogenic sources
Survey methodology This review summarizes what is known of inorganic paleogeochemistry in the Laurentian Great Lakes, itemized by metallic elements

Summary

Introduction

An understanding of past conditions is essential for potential remediation efforts in an aquatic system because it can be used to estimate natural baseline, remediation targets, timing and causes of impacts, and positive effects of existing remedial efforts. Kemp & Thomas (1976b) and Kemp et al (1978) considered Na a conservative element in their cores from Lakes Ontario, Erie, Huron, and Superior over the period from pre-settlement to the early 1970s and observed relatively stable concentrations over the interval.

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